Watching the Democrats’ fourth debate Tuesday night, you could see the candidates implementing this advice. They’d mention Joe Blow in their state who said X, or Jane Blow who called their office with Y problem. They commonly use techniques such as: “The voters I speak to aren’t preoccupied with the elite concerns of Washington or New York. The voters I speak to are concerned about . . .” and then the candidate fills in the policy he or she is touting.

That’s okay as far as it goes, but politics by anecdote should have some limits, because, as a wag once said, “The plural of anecdote is not data.” Relying on anecdotes alone is how you get the anti-vaccine movement and other dangerous delusions. “I knew a little boy who was totally normal and chatty until he got the MMR shot, and then he became autistic.” That’s tragic, but the data show that across large populations, there is no link between vaccines and autism. On the contrary, vaccines are a key public-health benefit.

Politicians owe it to us to ensure that when they use examples, they are using them to illustrate larger truths, not to mislead.

Elizabeth Warren fails this test. For someone who touts herself as a scholar, she resorts to anecdotes in most disingenuous fashion.